System for a hybrid vehicle; hybrid vehicle operated by the system and device for power

ABSTRACT

A hybrid vehicle control and operating system, a hybrid vehicle operated by the system, and a power supply arrangement for the hybrid vehicle where the drive of the hybrid vehicle is performed only by an electric motor driven by a generator under average power conditions and, under maximum power conditions, is driven by the generator and also by a battery bank that provides complementary energy to the electric motor. The bank of batteries accumulates energy exceeded by the generator and/or electric motor when the vehicle is under deceleration conditions or even stopped. The generator is driven by an internal combustion engine that supplies mechanical energy to the generator so that it can supply electric power to the electric motor and to the battery bank.

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/BR00/00108 which has an Internationalfiling date of Oct. 4, 2000, which designated the United States ofAmerica and was published in English.

SUMMARY OF THE INVENTION

The present invention refers to an operating system for a hybridvehicle, as well as to the hybrid system that is operated by thementioned system. The present invention also deals with the device thatintegrates the mentioned system and that has as function to providepower supply and accumulation. More specifically, it refers to a hybridsystem and a hybrid vehicle driven solely by an electric motor driven bymeans of a generator driven by an internal combustion engine.

The “Hybrid Vehicle” terminology is usually applied to vehicles usingmore than one power source for its displacement. Preferably, this nameis being used for vehicles that use an internal combustion engineassociated with equipment for the generation of electric power “onboard”. The electric power, which, in turn, is used to drive a tractionelectric motor that can operate independently and/or associated to theinternal combustion engine to drive the vehicle wheels. There is a verywide variety of set up and vehicle types that can be classified as“hybrid”.

The hybrid traction or driving systems are known as possessing a doublepower source. A specified type of hybrid system is the one using theelectric power from an electric motor and equipped with an internalcombustion engine, both of which are used to drive the vehicle. Thevehicles inherent to such systems are known as hybrid vehicles usingdual traction. Such is the system described in the U.S. Pat. No.5,513,719 published on May 7, 1996, that shows an internal combustionengine and an electric motor acting alternatively as vehicle tractionsource. The dual system to be applied needs a special driving ortransmission system, which is the object of U.S. Pat. No. 5,513,719.

These systems would be proper for the use in smaller vehicles such aspassenger cars for urban use in which the power requirement of thecombustion engine would be considerably smaller.

In the case of use of this dual system for bigger vehicles, such ascollective vehicles using, for instance, diesel fuel, the combustionengine would necessarily have considerably higher power, which wouldalso give rise to much bigger dimensions.

In the same way, as electric motor in this system, evidently when usedin a bigger vehicle, would require to be supplied solely and exclusivelyby the power supply element, such as battery which would logicallyrequire more charge and have a larger dimension in order to feed alarger size vehicle, fed by the electric system alone, when selected bythe control system.

So, such a solution is not proper to be used in larger size vehicles,such as a collective vehicle.

Therefore, the first objective of the present invention is to provide asystem to be used with any kind of vehicle, including collectivevehicles with diesel fuel, that dispense with the need for specifictransmissions and uses solely the electric motor as the driving engine.Thus, the adoption of the proposed system, would give rise, as firstconsequence, the elimination of the vehicle gearbox. Obviously, thevehicles using the hybrid system of this invention present these andother significant advantages as compared with vehicles moved by aconventional internal combustion or the vehicles using solely battery.

Another object of the present invention is to provide a hybrid vehicleequipped with the hybrid system of the present invention, which isprovided with an internal combustion engine that operates at a constantrotation and close to the rotation of the engine maximum torque, i.e.,it can be set to work close to the optimum point of less fuelconsumption and pollutant emission, that provides a significantreduction in the emission of gases to the atmosphere, that has beenproven in practical measurements that indicate a significant reductionof the pollutants emission, achieving a decrease of up to 60%.

It is an additional objective of the present application, to providedevice for power supply and accumulation which operates alternatelyfeeding power to the electric motor or accumulating power into a batterybank thus working as a true energy lung.

In hybrid vehicles with dual traction or driving or in electric vehiclesof the state of the art, when operated with electric motor as thedriving engine, this power required to move them come from poweraccumulators, also called battery banks. Usually, these battery bankshave the capacity to move the vehicle for a certain time, depending onthe vehicle use conditions—speed, transported load, etc., until theelectric charge is reduced and it is necessary to replace this batterybank or stop the vehicle during the time required to recharge thebattery bank from an external source.

The proposed system presents several advantages related to the usualhybrid systems in the state of the art, which will be described later inthis document. Similarly, the advantages obtained by the vehicleincorporating the proposed hybrid system, as well as the adoption of theBattery Bank, acting as a true energy lung, will be emphasized herein.

To give an example, but not to limit the scope, the description of thesystem and vehicle proposed, is based on their use in collectivevehicles, such as a bus, moved by diesel as fuel. With the systemproposed in the present invention, the diesel engine works always in aconstant rotation and driving a power generator that supply the tractionelectric motor with electric power and the surplus of this electricpower goes to charge the battery bank. Therefore, the diesel engine canbe set to work at its optimum point for a less combustible consumptionand a reduced pollutant emission. Practical measurements indicate thatpollutant emissions are reduced in a significant way, and one can get upto 60% decrease. The fuel consumption is also very reduced, as theengine is not submitted to the successive acceleration and decelerationthat characterize the operation in a traditional internal combustionvehicle.

The use of a battery bank, only as an “energetic lung” allows that thisbattery bank is small, with capacity much lower than one that would benecessary to operate a vehicle moved only by batteries. As a magnitudeorder, the capacity (and the weight) of the battery bank necessary forthe operation of the hybrid vehicle described herein is about one tenth({fraction (1/10)}) of the one that would be necessary to operate thesame vehicle if it was moved only by batteries. In addition, the hybridvehicle autonomy is almost unlimited (it depends only on the combustibletank), on the contrary of a battery vehicle, that presents a veryrestricted autonomy, due to the need for recharging or replacing thebattery bank within times somewhat short (hours of operation). Inaddition, due to the fact that, in the hybrid vehicle, batteries neverhave deep discharge, its lifetime increases very much, as compared tothe service life that they present in vehicles solely moved withbattery, where, at the end of each cycle, they are completelydischarged. In this way, the use of a battery bank operating as anenergy lung, i.e. supplying the electric motor with electric power andbeing recharged by the power generated by the generator that is drivenby the combustion engine every time the battery charge is reduced,allows, in addition to a greater autonomy to the vehicle, also that thementioned hybrid system of the present invention, is, by means of aresizing of the dimensional design, be used in any type of vehicle,whether light or heavy vehicles; in this last case, it would be, forinstance, a collective vehicle moved by diesel.

In addition, as the power “peaks” are supplied by the battery bank, theengine power, such as a diesel engine, (and the accompanying alternator)can be reduced in a remarkable way. In a traditional vehicle, theinternal combustion engine needs to be dimensioned to supply the “peak”power (maximum power) required by the work conditions, even if, most ofthe times, it operates with very lower power.

In the hybrid traction system described herein, the combustion engine,like the diesel engine, needs only to be dimensioned to supply the workaverage power, as the “peaks” are supplied by batteries, and during the“valleys”, the exceeding power is used for battery recharging. Theengine power reduction of the diesel engine becomes an additional factorto the reduction of the fuel consumption and of pollutant emission.

For the same reasons, it is quite less the noise indices from engine,what also causes the decrease of the sound pollution.

Therefore, it is one of the main objectives of the present invention toprovide the hybrid vehicle which needs lower fuel consumption, lower airpollutant emission, mainly when it is under urban utilization condition,and less noise level, so contributing to the decrease of soundpollution.

The conventional vehicle with internal combustion have an unique batteryand exclusively for their ignition and lighting system, being thisbattery small and of little use. In the electric vehicles only moved bybattery, it is necessary to use a great amount of batteries to get thepower required by the traction motor. These batteries, in addition toprovide limited autonomy to the vehicle, due to the low capacity ofaccumulate charge that they have, need frequent recharges, and thehigher the vehicle use, the greater the need of recharge frequency. Inthe hybrid vehicles, with traction solely by means of electric motors,as in the U.S. Pat. No. 5,428,274—issued on Jun. 27, 1995, the electricmotor is fed by batteries that are charged by means of the generator,being discharged to supply charge to the engine. In this case, thebattery acts constantly, which will require frequent conditions ofelevated charge for this type of battery, as described in this patent.If the battery was used to supplement the electricity within the regionbetween 60% of maximum power and 100% of the maximum power, batterywould need a higher capacity, becoming bigger and heavier. Instead ofthis, when the power requirement is between 60 up to 100% of maximumpower, this patent of the State of the Art uses as solution theutilization of internal combustion engine, to supply the batteryincapacity to act within this power range.

Such a solution has as disadvantages the fact that the battery needsconstant charge in the power range of up to 60% of the maximum power andthe use of a internal combustion engine with equivalent power to themaximum power of the electric motor.

In this case, the engine is the one acting as an “Energy Lung”. Toreach, as indicated in the patent of the state of the art, lowerdimensions and weights for the battery system, the previously proposedsolution evidently would require an internal combustion enginedimensioned to the power equivalent to the electric motor maximum power,what results in a engine with higher dimensions and weights than if onlybatteries were used as power suppliers, what is indicated as undesirablein the reference, due to the high weights and dimensions that such asystem would cause. Another drawback of this solution is the highereconomic value to use of the engine.

Aiming at solving these drawbacks of the State of the Art on thisapplication, a solution is proposed where a “battery bank” is used thatworks as an “energy lung”, that operates supplying power on occasions ofmaximum power and accumulating power during situations of low power,differently from the mention where the engine works with such anobjective. Obviously, the combustion engine and the generator driven bysaid engine, do not need to be dimensioned for extreme demandconditions.

Consequently, the engine power, weight and size of internal combustionengine and the generator, required to operate the vehicle, will besignificantly reduced. This will make also possible the use of thesystem proposed in the present application in light vehicles. This isdue to the fact that on every vehicle, the power used depends, at anymoment, of the vehicle operating conditions, reaching highvalues—maximum power—during accelerations and climbing slopes, andreduced values during decelerations or down slopes. Between these twoextreme situations, the average power is consumed.

One of the main objectives of the present invention, therefore, is toprovide one device of power supply and accumulation such as a battery,and, more specifically, an “energy lung” of small batteries, with muchlower capacity than the ones that would be required to operate a vehicleonly moved by batteries, and that acts in supplying energy at maximumpower occasions and accumulating energy during situations of low or nopower. In given situations, power “peaks” can reach from two to threetimes the required average power, and the “valleys” can arrive to zero.The exact values depend again on the roadway, traffic conditions anddriver's driving style. The simple reduction in the engine dimensioning,for instance, fueled by diesel, and in the dimensioning of thegenerator, that, instead of being dimensioned to supply the “peak”powers they need only to supply the average power, what implies inconsumption and pollution, reductions as already indicated.

Other objective and additional advantages of the applicability of thepresent invention will be shown in the detailed description below, takenin conjunction with the attached drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows in a schematic way the operation system of a hybridvehicle, as well as its devices for power supply and accumulation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, we present in a simplified way the functional componentsshown in schematic form in order to ease the understanding of the workand control components inter-related with the functioning of the globalsystem.

The hybrid traction system described herein has on board an electricpower double source, namely:

An engine-generator including an internal combustion engine (1) thatdrives a generator (2) (usually an alternator), also identified on FIG.1 as M (internal combustion engine) and G (generator/alternator); and

A battery set or energy lung (3), as seen on figure one, hereinafteridentified as BAT.

The engine-generator set function is to provide electric power to theelectric motor (4) identified on FIG. 1 and hereinafter as ME.

This electric motor (4) is the only engine to drive the vehicle, andunder no instance does the internal combustion engine (1) participate inthe function of driving the vehicle wheels. As one can see on theFIGURE, the electric motor (4) ME, is connected to a speed reducer (5)which, in turn, is directly connected to driven wheels (6) of the hybridvehicle.

In other words, the vehicle driving is always made by the electric motor(4) and in no instance does the internal combustion engine (1) directlyparticipate in the shaft drive.

The energy lung function (3) or battery bank BAT is to accumulateelectric power, to be used only in the moments of high energy demand,as, for instance, during quick accelerations or ascending slopes.

The internal combustion engine (1) is always kept in rotation orconstant angular speed during all operating ranges of the hybridvehicle, by means of the rotation regulator (7), hereinafter identifiedas RR, in accordance with diagram on FIG. 1. This regulator (7) makespossible the internal combustion engine (1) to work always at a constantrotation, regardless the power requested by alternator/generator G. Thischaracteristic of constant rotation provides significant improvements onthe pollutant emission and fuel consumption, as the internal combustionengine can be optimized to this operating range, and is not submitted toaccelerations and decelerations usually required in the trafficoperations.

In a generic way, the functioning of the system is processed on thefollowing manner:—the internal combustion engine (1) M provides therequired power, at a constant rotation, to the alternate currentgenerator (2). The power in the form of alternate current generated bythe generator (2) is rectified by means of rectifier (8), alsoidentified in the FIGURE as RET and turned into direct current. By itsturn, this demand of direct electric current is required by the drivingelectric motor (4) ME by the demand of the speed control (9) hereinafteridentified as SCV, which is operated by the driver of the hybridvehicle, depending on the acceleration, deceleration, ascensions andpassing, in short, on traffic conditions and driving conditions of thevehicle. In situations such as slope ascension or passing, where thepower required by the electric motor (4) is higher than the electricpower capacity of the generator group, as called the assembly internalcombustion engine (1) and generator (2), comes into action, as acomplement of the latter, the battery bank (3), all of this systemmanaged by a control electronic system (10), hereinafter identified as“SEC”.

In a more specific manner, the electronic system SEC may be explained asfollows:

The electric motor (4) requires that a given electric power bedelivered, in order to perform the function that is required from it bythe driver of the hybrid vehicle at every moment (accelerate or brake).In this way, when the driver positions the accelerator pedal, which isdirectly connected to the speed control (9), until a given position (forinstance, 30% of its total course), in reality is requesting a givenacceleration of the vehicle (30% of the maximum design speed, in theexample given). So, the electronic control system (10) receives theinformation about the accelerator, and responds to the driver control byacting on the armature chopper and controlling the chopper to increasethe armature current of the driving electric motor (4). At the sametime, as the electric motor (4) increase its speed, the electroniccontrol system (10) acts on the motor (4), allowing the electric motorarmature voltage increase. Therefore, increase of power is transmittedto the drive motor up to achievement of the desired acceleration. Thebraking is started when the driver presses the brake pedal.

During braking, the inverse sequence occurs. The acceleration duringbraking becomes negative, the accelerator pedal is in its rest positionand the electric motor (4) starts to generate power, instead ofabsorbing it.

The absorbed electric power, as well as the power generated, arecalculated by means of a power electronic sensor (not shown on diagram),an electric motor armature current sensor within (4), and from anelectric motor field current sensor within (4).

A closed loop system, resident in the electronic control system (10) isresponsible for controlling the absorbed or generated power, by means oftwo choppers, IGBT (that are integral part of SCV (9)), one of themacting on the electric motor armature (4) and the other one acting onthe electric motor field (4), making the electric power supplied to itto be that necessary to cause the acceleration required by driver whenhe first pressed the accelerator up to a given position or that theelectric power generated, in case of deceleration and/or braking, issent to battery bank (3) for recharge. All these sensors allowcalculation of the instantaneous power and of the driving electric motorspeed.

The control electronic system (10) acting to control the voltages andcurrents that go through the several components of the system, workswith six (6) regulators, with closed loop circuit, acting simultaneouslyand in a coordinated way, namely:—an electric motor armature currentregulator, an electric motor field current regulator, and an electricmotor armature voltage regulator jointly control the torque and thespeed, and therefore, the power absorbed or generated by the electricmotor (4). A voltage regulator (11) of the generator (2) is responsiblefor the control of voltage generated by generator (2), which ismaintained constant regardless of the charge supplied by the generator.A maximum current regulator of the generator acts to limit the maximumcurrent supplied by generator (2) and its function is to protect thegenerator, avoiding the generator from supply currents above its maximumdesign value, and, at the end, a maximum charge current regulator of thebattery bank has the function of limiting battery charge regimen,avoiding the batteries to be damaged by excessive charge currents. Thisregulator acts on the generator (2) and reduces the output voltagewhenever the charge current approaches a dangerous value.

Regarding the rectifier (8) output voltage regulator, which function isto maintain constant voltage for feeding the electric motor (4),regardless of it's the electric motor load, it must be noted that thiscontrol is made by means of a voltage regulator by closed loop circuit(11)—RV, that acts in a generator field (2) and that uses a generatorarmature voltage detector as a feedback signal. The generator fieldcurrent is, then, controlled by means of an IGBT that responds to thecontrols of the voltage regulator (RV 11), always trying to keeparmature voltage constant, regardless of the load fluctuations (demandof the electric motor “ME”). The generator (2) voltage is only reducedif excessive currents of battery charges are verified. This function isperformed by the maximum current regulator of the battery bank (3) asmentioned above.

As a final remark, it must be emphasized that the battery is rechargedwhenever there is a “surplus” of the power generated by the alternator(or by the driving motor), in the moments where the power demand fordriving is small, i.e., in descending slopes or during braking.

In addition to the previous explanations, it is clear that the proposedhybrid vehicle autonomy will not depend on the (small) power accumulatedin the battery bank, but only on the fuel quantity available on the tankand on the consumption of the chosen combustion engine.

In turn, the consumption will depend on the necessary electric motorpower and on the characteristics of the course, similarly to aconventional vehicle, for instance, a diesel moved vehicle.

What is claimed is:
 1. A hybrid vehicle controlling and operating systemincluding an internal combustion engine (1) operable at a constantrotation; a generator (2) driven by the internal combustion engine andproviding a constant output voltage; a direct current electric motor (4)receiving power from said generator and providing the sole and exclusivedrive source for the hybrid vehicle; a rechargeable battery source (3)connectable with the electric motor such that the battery source outputvoltage is provided as the input voltage to the electric motor only whenthe generator power supplied to the electric motor is insufficient tomeet the power requirements of the electric motor, said battery sourcemaintained charged by surplus charge from the generator and chargegenerated by the electric motor; an electrical control system means forcontrolling the electric power supply to said electric motor includingmeans for supplying power to the electric motor only from the generatoruntil the maximum power of the generator is insufficient to supply thepower requirements of the electric motor, and for supplying additionalpower from the battery source only when the maximum power of thegenerator is insufficient to supply the power requirements of theelectric motor, said electrical control system means further includesmeans for maintaining and controlling the charge and discharge of saidbattery source including evaluating the charge condition of the batterysource, the surplus charge generated by the generator and the electricmotor.
 2. The hybrid vehicle controlling and operating system of claim 1wherein said electrical control system means further comprises means formaintaining the internal combustion engine operating at a constantrotation over all load conditions.
 3. The hybrid vehicle controlling andoperating system as claimed in claim 1, further comprising a speedcontrol mechanism responsive to an accelerator pedal position, andwherein said electrical control system controls the current supplied tothe electric motor in response to said speed control mechanism.
 4. Ahybrid vehicle controlling and operating system including an internalcombustion engine (1) operable at a constant rotation; a generator (2)driven by the internal combustion engine and providing a constant outputvoltage; a direct current electric motor (4) receiving power from saidgenerator and providing the sole and exclusive drive source for thehybrid vehicle; a rechargeable battery source (3) connectable with theelectric motor such that the battery source output voltage is providedas the input voltage to the electric motor only when the generator powersupplied to the electric motor is insufficient to meet the powerrequirements of the electric motor, said battery source maintainedcharged by surplus charge from the generator and charge generated by theelectric motor; an electrical control system means for controlling theelectric power supply to said electric motor including means forsupplying power to the electric motor only from the generator until themaximum power of the generator is insufficient to supply the powerrequirements of the electric motor, and for supplying additional powerfrom the battery source only when the maximum power of the generator isinsufficient to supply the power requirements of the electric motor,wherein said electrical control system means further comprises means forsensing and controlling the direct current electric motor armaturecurrent and motor voltage and the motor field current for controllingthe torque and speed of the electric motor; means for sensing andcontrolling the generator voltage and current to maintain a constantgenerator voltage and variable current output as a function of theelectric motor load requirements; and means for controlling and managingthe charging and discharging of the battery source.
 5. The hybridvehicle controlling and operating system as claimed in claim 4, whereinsaid constant rotation of the internal combustion engine issubstantially at the engine maximum torque.
 6. The hybrid vehiclecontrolling and operating system as claimed in claim 4, wherein theinternal combustion engine works in one-to-one power relationship withthe generator for constant supply of the electric motor.
 7. The hybridvehicle controlling and operating system as claimed in claim 4 furthercomprising means for supplying any surplus of energy generated by thegenerator and not used by the electric motor to the battery source forconstant maintenance of the maximum charge thereon.
 8. The hybridvehicle controlling and operating system as claimed in claim 4, whereinthe electrical control system means controls a constant rotation of theinternal combustion engine through the actuation of a rotation regulator(7).
 9. The hybrid vehicle controlling and operating system as claimedin claim 4, wherein the electrical control system means includes meansfor controlling the field current of the generator through actuation ofa voltage regulator, based on the maintaining of voltage and currentconditions at the electric motor.